Check valve for hydraulic control system

ABSTRACT

This invention concerns a system using a hydraulic control line to control a downhole safety valve located in a string of tubing suspended in a well bore drilled in the earth. The hydraulic control line is in the space between the tubing string and the casing of the well bore. A special lever actuated valve means is used in the wall of the tubing string at the point where the hydraulic line connects into the tubing string downhole. The insertion of a wireline retrievable safety valve holds the lever actuated valve open. When the safety valve is removed the force of the tubing pressure causes the lever actuated valve to close.

United States Patent 1191 1111 3,777,813

Dendy et al. Dec. 11, 1973 CHECK VALVE FOR HYDRAULIC 2,780,290 2/1957Natho [66/72 CONTROL SYSTEM 4/1945 Laird et al. 166/224 s [75]Inventors: Jackie D. Dendy; Robert D.

Johnson, both of Lafayette; Robert M. Peevey, New Orleans, all of La.

[73] Assignee:

2/1963 Tausch 7/1940 Toney Amoco Production Company, Tulsa,

[1.8. CI. 166/72, 166/224 S Int. Cl E2lb 33/03, E2lb 43/12 Field ofSearch 166/72, 724 S 2: 2:37); 'li fii ikjkiiiiinu."2225 PrimaryExaminer-James A. Leppink Attorney-Paul F. l-lawley et al.

571- ABSTRACT This invention concerns a system using a hydraulic controlline to control a downhole safety valve located in a string of tubingsuspended in a well bore drilled in the earth. The hydraulic controlline is in the space between the tubing string and the casing of thewell bore. A special lever actuated valve means is used in the wall of,the tubing string at the point where the hydraulic line connects intothe tubing string downhole. The insertion of a wireline retrievablesafety valve holds the lever actuated valve open. When the safety valveis removed the force of the tubing pressure causes the lever actuatedvalve to close.

4 Claims, 2 Drawing Figures PAIENIEnMc 11 um 3.777.813

FIG.2

FIG. I

CHECK VALVE FOR HYDRAULIC CONTROL SYSTEM BACKGROUNDOF THE INVENTION 1.Field of the Invention Thisinvention relates to downhole safety valves,especially those used in strings of tubing used to produce oil and gasfrom underground deposits. 4

2. Setting of. the Invention Commercial quantities of oil andgas arefound deep within the earth. These deposits are recovered by drilling awell bore to the deposit. The well bore is lined with a steel casingwith cement betweenthe casing and the borehole wall. A string of tubing,which is really small diameter pipe, e.g., 2% inches, is suspendedinside the casing from the surface to the deposit. A packer seals theannular space between the exterior of the string of tubing and'thecasing at a level just above the location ofthe deposit of oil=and gas.The oil and gas are produced through perforations in the casing upthrough the tubing string to the surface.

If the deposit of oiland gas is found in water covered areas, such: asthe Gulf of Mexico, special subsurface safety valves are required tobeset inthe tubing string at a position below the mudline. The reason forthis is if the wellhead equipment or casing'above the ocean floor isdamaged or broken, the subsurface safety valve will close and preventany escape of oil-.or gas. One particularly popular type subsurfacesafety valve is the type which is held open by a separate hydraulicfluid from a hydraulic control-line. This hydraulic flow line normallyextends from the surface to the downhole safety valve and is positionedin the annulus between the string of tubing and the casing. In many ofthe older wells, the casing cannot withstand as high a pressure as canthe smaller tubing string. Allowing tubing pressure to the tubing-casingannulus in high pressure wells is dangerous even on new wells; thus,common practice is to prevent this occurrence on. such high pressurewells. That is one reason why high pressure production is through thetubing string.

We have discovered that under certain conditions there is a potentialhazard to the well casing. This can occur if the hydraulic control lineis broken or develops a leak at a time when the safety valve is not inposition. Then the higher pressure fluid in the tubing can escapethrough the hole in the control line thus raising the pressure in theannulus. If the pressure is sufficiently high it can cause failure ofthe casing. Our invention discloses a system to eliminate this potentialhazard.

BRIEF DESCRIPTION OF THE INVENTION This invention concerns a systemusing a hydraulic control line to control a downhole safety valvelocated in a string of tubing suspended in a well bore drilled in theearth. The hydraulic control line is in the space between the tubingstring and the casing of the well bore. The lower end of the hydrauliccontrol line leads to a tubing port in a special section of the tubingstring. There are seals on the safety valve'so that when it is inserted,the tubing port is sealed from the remainder of the string of tubing,but is in fluid communication with the hydraulic piston of the safetyvalve. A special lever actuated valve means is used in the wall of thetubing string at the point of the tubing port operable to close thetubing port. The insertion of a wireline retrievable safety valve holdsthe lever actuated valve open and removal of the safety valve permitsthe lever actuated valve to close.

BRIEF DESCRIPTION OF THE DRAWINGS Various objects and a betterunderstanding of the invention can be had from the following descriptiontaken in conjunction with the drawings in which:

FIG. 1 is a donwhole view partly in section showing a subsurface safetyvalve and hydraulic control line system featuring our invention.

FIG. 2 illustrates an enlarged view showing the lever actuated valve ofFIG. 1 for shutting off the interior of the tubing from the hydrauliccontrol line.

DETAILED DESCRIPTION OF THE INVENTION Attention is first directed toFIG. 1 which illustrates a casing 10 suspended in a well bore 12. Thesection of FIG. 1 is typically located in a well drilled in awatercovered area and is located at a level below the mudline. Suspendedwithin casing 10 is a string of tubing 14 which extends upwardly to thesurface to conventional wellhead equipment not shown. The lower end oftubing 14 extends downwardly to the producing interval in a conventionalmanner. A wireline retrievable safety valve 16 is suspended in tubingstring 14. A typical and suitable safety valve 16 is commerciallyavailable from Otis Engineering Corporation, Dallas, Texas, and is de'scribed in their l96667 catalog, page 384] as an Otis Wireline RemovableBall-Type Safety Valve." A special section 1 8, which is sometimesreferred to as a landing nipple, is provided in tubing string 14. Anexternal hydraulic control line 20 is provided in annulus 22 betweencasing 10and tubing 14. This hydraulic control line extends to thesurface or other point where hydraulic fluid under pressure can beobtained.

Hydraulic control line 20 is connected into cavity 24 in landing nipple18. Cavity 24 is isolated from the interior of tubing 14 upon insertionof safety valve 16 by upper seals 26 and lower seals 28 which are on theexterior walls of safety valve 16. Safety valve 16 also includes lockingmeans 30 and wireline latching neck 32. In its normal operationhydraulic fluid is supplied through hydraulic control line 20 intocavity 24 and into a port 34 which will actually hold the valve section36 in an open position. The internal means of the safety valve 16 willnot be shown as they are well known and the details of these are not apart of this invention. It is sufficient to say that if hydraulicpressure is relieved or reduced on line 20 either by intentional meansor by breakage of the line, the valve closes and no fluid can flowupwardly through tubing 14. This prevents pollution in event of a severestorm or ship or other catastrophe breaking the wellhead equipment.

The entire valve 16 must be retrieved periodically for checking or forreplacement. As mentioned above in the setting of the invention, whenwireline retrievable safety valve is pulled or removed, and if hydraulicline 20 is broken, if it were not for our invention, then the highpressure of the fluid in the tubing string would be exerted against thecasing. This presents a grave and dangerous situation because there is adistinct possibility that the casing may-be ruptured. We eliminate thisproblem by our invention. We provide a lever actuated check valve 38.This can be seen more clearly seen in FIG. 2. Shown in FIG. 2 is valveseat 40 which is formed in the wall of the landing nipple at the inletof hydraulic line 20. This is arranged to receive ball valve 42 of valvemeans 38. This valve means includes a pivot 44 about which the valvemeans rotate. Valve means 38 includes a lever 46 and valve support arm48. Members 46 and 48 are rigidly fixed together and preferably are madean integral part which pivots about pivotal point 44. A spring 50 isprovided and biases the valve 42 in .a direction indicated by arrow 52toward seat 40. When the retrievable valve means 16 is inserted intolanding nipple 18 it strikes lever 46 and shoves it into the positionshown in FIG. 2. This causes valve 42 to be held in an open positionaway from seat 40. Then while the safety valve is in the position shownin FIG. 1, hydraulic fluid from control line 20 is effective to operatesafety valve 16. However, when valve 16 is removed, springs 50 causesvalve 42 to seat in seat 40. Force exerted by the tubing pressure alsoaids in closing the valve. Thus, fluid in the tubing'string 14 cannotflow into control conduit 20. Thus, even though line 20 may be damagedand contain a leak, the high pressure fluid in tubing 14 cannot enterannulus 22 and therefore will not apply the high pressure to casing 10.

While the above description has been made in considerable detail,various modifications can be made thereto without departing from thespirit or scope of the invention.

We claim:

1. In a system in which a retrievable safety valve is set in a tubingstring in a well bore and is controlled by hydraulic control lineextending from a source of controlled hydraulic fluid to a port in thetubing string adjacent the safety valve, the improvement whichcomprises:

a cavity in the wall of said tubing string; i

said port opening into said cavity;

a seat in said port in said cavity;

a valve for said seat;

first means biasing said valve toward said seat;

second means extending into the interior of said tubing string operableto hold said valve away from said seat when said safety. valve contactssaid second means upon insertion of said safety valve in said tubingstring adjacent said cavity.

2. in a system in which a retrievable safety valve is set in a tubingsection in a tubing string in a well bore and controlled by hydrauliccontrol line extending from a source of controlled hydraulic fluid to aport in said tubing section adjacent said safety valve, the improvedtubing section comprising:

a cavity in said tubing section;

a seat in said cavity at the opening of said port;

a valve;

a pivot in said cavity;

a pivoting unit pivotally mounted on said pivot and including (a) an armwhich supports said valve at its outer end and (b) a lever, the pivotbeing between said arm and said lever, said lever extending out of saidcavity into the passage of said tubing section when said valve is seatedin said seat.

3. The device as defined in claim 2 including means urging said valvetoward said valve seat.

4. A device as defined in claim 3 in which said means is a spring.

1. In a system in which a retrievable safety valve is set in a tubingstring in a well bore and is controlled by hydraulic control lineextending from a source of controlled hydraulic fluid to a port in thetubing string adjacent the safety valve, the improvement whichcomprises: a cavity in the wall of said tubing string; said port openinginto said cavity; a seat in said port in said cavity; a valve for saidseat; first means biasing said valve toward said seat; second meansextending into the interior of said tubing string operable to hold saidvalve away from said seat when said safety valve contacts said secondmeans upon insertion of said safety valve in said tubing string adjacentsaid cavity.
 2. In a system in which a retrievable safety valve is setin a tubing section in a tubing string in a well bore and controlled byhydraulic control line extending from a source of controlled hydraulicfluid to a port in said tubing section adjacent said safety valve, theimproved tubing section comprising: a cavity in said tubing section; aseat in said cavity at the opening of said port; a valve; a pivot insaid cavity; a pivoting unit pivotally mounted on said pivot andincluding (a) an arm which supports said valve at its outer end and (b)a lever, the pivot being between said arm and said lever, said leverextending out of said cavity into the passage of said tubing sectionwhen said valve is seated in said seat.
 3. The device as defined inclaim 2 including means urging said valve toward said valve seat.
 4. Adevice as defined in claim 3 in which said means is a spring.